A requisite for the maintenance of fluids is that they be sealed within a container sufficient to prevent them from breaking down, evaporating, or drying out. A requisite for a disposable container is that it be simple and economical to manufacture and easy to use.
In U.S. Pat. No. 4,599,008, issued July 8, 1986, for a "Fingernail Polish Capsule and Plunger," the disclosure of which is incorporated herein by reference, there is described a sealed unit in the form of a cartridge containing nail polish, a slidable brush attachment, a piston, and a plunger. It is to be used in a reusable handpiece. When the cartridge is placed into the handpiece, the brush attachment slides axially to automatically force open a panel at one end of the cartridge, that end being closed by a separately formed plug which has a sealed fit in the cartridge. Next, a plunger is utilized to displace a removable panel at the opposite end of the cartridge. That removable panel sits on a piston and is moved into the cartridge by further movement on the plunger which also moves the piston, thereby forcing the liquid nail polish into the brush attachment.
As noted therein, nail polish is customarily sold in bottles with the closure cap having an attached brush which is used to apply the polish. Such bottles contain more polish than is required for a single application so that after use the bottle must be reclosed and stored. Various techniques have been adapted to store such containers, including placing them in refrigerators. It is remarked that there has, however, been no satisfactory and convenient solution to solvent loss. In fact, it is stated, there is a solvent loss in the customary nail polish bottle arrangement during storage. While the invention of the '008 patent is said to solve that solvent loss problem, it has been discovered that various aspects of the device disclosed therein make its use as a disposable application unit inconvenient and expensive. First, the device is complicated from a standpoint of manufacture, containing a number of intricate parts. Additionally, the '008 device must be used with a plunger-containing handpiece.